Polyoxometalate-Based Organic-Inorganic Hybrids as Heterogeneous Catalysts for Cycloaddition of CO2 with Epoxides and Oxidative Desulfurization Reactions

Self-assembly of polyoxometalates, transition metal salts, and 2,6-bis(2'-pyridyl)-4-hydroxypyridine (LOH) obtained four organic-inorganic hybrids [Co-2.5(LOH)(LO)(2)(H2O)(2)(PW12O39)]center dot 3CH(3)CN center dot 2OH (1), [Zn-1.5(LOH)(3)]center dot(PMo12O40)center dot CH3OH center dot 2H(2)O (2), [Cd-1.5(LOH)(3)]center dot(PW12O40)center dot 2CH(3)OH center dot 1.5H2O (3), and [Mn(LOH)(2)]center dot(PW12O40)center dot 2CH(3)CN center dot H3O (4). Hybrid 1 exhibits an extended chain, which could be further connected into a 3D supramolecular architecture by H-bonds. Hybrids 2-4 feature monomolecular structures, which are further bridged via H-bonds to yield charming 3D supramolecular structures. Noteworthy, 1 and 2 can be employed as recyclable and highly efficient heterogeneous catalysts. The activated 1 displays a high catalytic activity for the cycloaddition reaction of CO2 and epoxides. Hybrid 2 exhibits an excellent catalytic performance for the oxidative desulfurization reaction.